Transparent resin materials with near infrared absorption characteristics possess both clearness and ability of heat radiation shielding by near infrared absorption. These features make them attractive as light-admitting materials for buildings, windows of transport vehicle, ceilings, doors, arcades, garages, sunrooms, greenhouses, etc.
Their ability of absorbing near infrared radiation also promises their uses in such applications as eye-protecting lenses and other safety glasses, infrared-sensitive filters, and photosensitive materials using semiconductor laser beam sources.
As a conventional transparent resin material with near infrared absorption characteristics, a polymer prepared by dissolving tungsten hexachloride and tin chloride in methyl methacrylates for polymerization is known (U.S. Pat. No. 3,692,688).
Other near infrared absorbers are, for example, a thiol-nickel complex (Japanese Patent Application Publication (Kokoku) No. 60-21294), chromium-cobalt complex salt (Japanese Patent Application Publication (Kokoku) No. 60-42269), anthraquinone derivative (Japanese Patent Application Public Disclosure (Kokai) No. 61-115958), and squarilium compound (Japanese Patent Application Public Disclosure (Kokai) No. 61-218551).
Instead of adding a near infrared absorber to resins, vapor deposition of aluminum, silver or other metal on one side of a polyethylene terephthalate film has also been practiced to manufacture a heat radiation reflecting film. The reflecting film, when laminated to a transparent resin material, achieves the dual effects of reflecting a heat radiation from the outside and suppressing an increase of the internal temperature.